Bind mount disk devices in chroot

Some operations need access to the disk device backing the image that's
being build, in particular for installing grub-pc. e.g. grub-install needs to write to the MBR to add
it's boot imgae and probed information.

To allow this bind mount the image device file,  all devices files for
the created partitions and the /dev/disk directory (for udev alias symlinking)
into a chroot when running commands in it.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>

actions/apt_action.go

@@ -41,7 +41,7 @@ func (apt *AptAction) Run(context *debos.DebosContext) error {
 	aptOptions = append(aptOptions, "install")
 	aptOptions = append(aptOptions, apt.Packages...)
 
-	c := debos.NewChrootCommand(context.Rootdir, context.Architecture)
+	c := debos.NewChrootCommandForContext(*context)
 	c.AddEnv("DEBIAN_FRONTEND=noninteractive")
 
 	err := c.Run("apt", "apt-get", "update")

actions/debootstrap_action.go

@@ -70,7 +70,7 @@ func (d *DebootstrapAction) RunSecondStage(context debos.DebosContext) error {
 		cmdline = append(cmdline, fmt.Sprintf("--components=%s", s))
 	}
 
-	c := debos.NewChrootCommand(context.Rootdir, context.Architecture)
+	c := debos.NewChrootCommandForContext(context)
 	// Can't use nspawn for debootstrap as it wants to create device nodes
 	c.ChrootMethod = debos.CHROOT_METHOD_CHROOT
 
@@ -140,7 +140,7 @@ func (d *DebootstrapAction) Run(context *debos.DebosContext) error {
 	}
 	srclist.Close()
 
-	c := debos.NewChrootCommand(context.Rootdir, context.Architecture)
+	c := debos.NewChrootCommandForContext(*context)
 
 	return c.Run("apt clean", "/usr/bin/apt-get", "clean")
 }

actions/run_action.go

@@ -81,7 +81,7 @@ func (run *RunAction) doRun(context debos.DebosContext) error {
 	var cmd debos.Command
 
 	if run.Chroot {
-		cmd = debos.NewChrootCommand(context.Rootdir, context.Architecture)
+		cmd = debos.NewChrootCommandForContext(context)
 	} else {
 		cmd = debos.Command{}
 	}

commands.go

@@ -66,8 +66,28 @@ func (w *commandWrapper) flush() {
 	w.out(true)
 }
 
-func NewChrootCommand(chroot, architecture string) Command {
-	return Command{Architecture: architecture, Chroot: chroot, ChrootMethod: CHROOT_METHOD_NSPAWN}
+func NewChrootCommandForContext(context DebosContext) Command {
+	c := Command{Architecture: context.Architecture, Chroot: context.Rootdir, ChrootMethod: CHROOT_METHOD_NSPAWN}
+
+	if context.Image != "" {
+		path, err := RealPath(context.Image)
+		if err == nil {
+			c.AddBindMount(path, "")
+		} else {
+			log.Printf("Failed to get realpath for %s, %v", context.Image, err)
+		}
+		for _, p := range context.ImagePartitions {
+			path, err := RealPath(p.DevicePath)
+			if err != nil {
+				log.Printf("Failed to get realpath for %s, %v", p.DevicePath, err)
+				continue
+			}
+			c.AddBindMount(path, "")
+		}
+		c.AddBindMount("/dev/disk", "")
+	}
+
+	return c
 }
 
 func (cmd *Command) AddEnv(env string) {